1. Field of the Invention.
This invention has relation to the dispensing of liquids by gravity at measured or fixed rates. The invention presents an apparatus which, when properly and accurately initially adjusted, will continue to feed liquid indefinitely at the same rate regardless of the source or height of liquid in the main supply chamber from which the liquid is being supplied.
2. Description of the Prior Art.
It has long been known to feed a liquid to be dispensed from a bottom of a liquid supply container which is suspended or supported above the point to which the dispensed liquid is to be delivered. Where the volume of liquid to be dispensed is relatively small per unit of time, the liquid flows from the supply container through a flexible deformable liquid delivery hose. An adjustable hose clamp valve encompasses the hose at a convenient location, and is manually adjustable to control the rate of discharge of the dispensed liquid from the supply container. Typically such supply containers are open to the atmosphere. As the level of liquid in the supply container drops due to the liquid flowing out of the container, the hydrostatic pressure decreases, and the adjustable hose clamp valve must be continuously adjusted to compensate for this pressure drop in order to attempt to maintain a uniform output from the supply container. As a result, in critical applications, such as the delivery of blood plasma to a living patient, an attendant skilled in the adjustment of the adjustable hose clamp valve must be almost constantly in attendance.
In order to feed liquids to be dispensed at uniform and/or variably controllable rates either by gravity or under otherwise induced pressure, expensive, complicated and relatively difficult to maintain measuring, metering and/or pumping devices have been developed. Relatively close precision can be obtained with some devices in this category; but because of expense, the bulk of such devices, and, consequently, the inability to have such devices available at the time and place they are needed has rendered them unsatisfactory for general usage.
Because of the necessity to constantly adjust the liquid supply flow valve with the constantly changing head of hydrostatic pressure to maintain uniform flow, it has been impossible to calibrate such a valve to control the flow from a liquid supply container into another body of liquid to make the feed of liquid from the liquid supply container proportional to the flow in the other body of liquid. For example, until the present invention, it has not been possible to provide a liquid supply flow valve in a gravity feed liquid supply apparatus which can be proportionally moved toward open and toward closed as flow of water in a municipal water supply increases and decreases.
It has been proposed to meter liquids in the laboratory by connecting the bottom of a large burette with a flexible hose connected to a capillary tube and to introduce air through the sealed top of the burette and down a thin capillary tube to a point near the bottom of the burette. In order to use this apparatus without completely disassembling it, an open sump tank, a siphon conduit open to the interior of the burette, and a pump open from the sump tank into the interior of the top of the burette must be provided. See reprint from The Journal of the American Oil Chemists' Society, July 1961 issue, Volume XXXVIII, No. 7, Page 380. Because this article appeared in July of 1961, and since it is not widely used today, it evidently did not render obvious the structure of the present invention.
No specific search was made on this invention; but the applicants and those in privity with them are aware of no prior art which is closer than that discussed above, and are aware of no prior art which anticipates the claims herein.